Agronomic response of ‘Michele palieri’ (Vitis vinifera L.) table grape to intraspecific diploid and interspecific tetraploid pollinizers

Yield and quality of grapes are markedly enhanced by cross-pollination although self-pollination ensures some level of berry set. Cross pollination is also employed to breed a new fruitful genotype to sustain the food to feed the increasing world population on the face of climate change. The present investigations were performed to reveal the effects of diploid and tetraploid pollinizers on the agronomy of ‘Michele Palieri’ table grape cultivar. For cross pollinations, the flower buds of the maternal cultivar were emasculated 5–6 d before bloom, while the clusters belonging to self- or free pollination groups were not emasculated. All the clusters including the pollinizers, except for free pollination, were covered with cheesecloth bags to exclude random pollination. Hand pollination was carried out for each cross-combination with hairbrushes when the stigma attains peak receptivity. Pollination was carried out two times (morning in the following day), while the flowers of self-pollination group were allowed to bloom and self-pollinate in the bags. The clusters of free pollination were left after labeling without isolation. The pollinizers had remarkably different impacts on the agronomy of maternal cultivar. The highest values on berry set (20.22 %), seed size (7.18 mm) and soluble solid content (15.5°Brix) were achieved when ‘Crimson Seedless’ was used as pollinizer. The clusters set berries poorly when the pollen of interploid tetraploid ‘Kyoho’ (13.46 %) was used. However, berry color was markedly improved by ‘Kyoho’ pollens with darker and more intense skin color. Cluster mass was significantly improved by external pollens of diploid cultivars resulting from better berry set and berry development in comparison with self-pollination. Berry mass values of free pollination and ‘Michele Palieri’ x ‘Italia’ treatments were 26.6 % and 22.8 % higher than that of self-pollination. The highest values on berry detachment and skin rupture forces were detected in ‘Michele Palieri’ x ‘Italia’ combination, while the lowest measures were on both parameters were found in self-pollination berries. Finally, the use of pollinizer cultivars, instead of monovarietal vineyard establishment, could be recommended to improve berry set and quality under vineyard or protected cultivation conditions. Tetraploid ‘Kyoho’ could be used in an interspecific and interploid breeding study as donor for unique characters.